Long Term Storage with Surveillance of Canadian Prototype Nuclear Power Reactors
- Atomic Energy of Canada Ltd., Chalk River Laboratories, Chalk River, Ontario, K0J 1J0 (Canada)
Atomic Energy of Canada (AECL) was originally formed by the government of Canada in 1952 to perform research in radiation and nuclear areas. In the mid 1950's Canada decided to limit itself to peaceful uses of nuclear energy and AECL embarked on several research and development programs, one of them being the development of nuclear power plants. This led to the development of the CANDU{sup TM} design of heavy water power reactors, of which there are now 29 operating around the world. This presentation discusses the present state of the first two CANDU{sup TM} prototype reactors and a prototype boiling light water reactor and lessons learnt after being in a long-term storage with surveillance state for more than 20 years. AECL facilities undergo decommissioning by either a prompt or a deferred removal approach. Both approaches are initiated after an operating facility has been declared redundant and gone through final operational shutdown. For the deferred approach, initial decommissioning activities are performed to put the facility into a sustainable, safe, shutdown state to minimize the hazards and costs of the ensuing extended storage with surveillance (SWS) or Safestor phase. At the appropriate time, the facility is dismantled and removed, or put into a suitable condition for re-use. AECL has a number of facilities that were built during its history, and some of these are now redundant or will become redundant in the near future. The deferred removal approach is part of AECL's decommissioning strategy for several reasons: 1. Reduction in radiation doses to workers during the final dismantling, 2. No facilities are available yet in Canada for the management of quantity of wastes arising from decommissioning, 3. Financial constraints presented by the number of facilities that will undergo decommissioning, compared to the availability of funds to carry out the work. This has led to the development of a comprehensive decommissioning plan that includes all of AECL's redundant and presently operating facilities. Several significant issues have arisen over the decades these reactors have been in the SWS phase. With the long time frames encompassed by this approach to decommissioning, the storage and maintenance of facility information for future decommissioning, and the knowledge and training of successive generations of staff to perform facility inspections and maintenance are major issues. Complacency of both staff and management is a potential issue. The problem arises primarily because these facilities have been put into a comparatively low hazard state, are remotely located, and not much changes over time and changes are slow. During the period that these facilities have been in this state, regulatory scrutiny and expectations have increased. This along with continuing changes in regulatory staff requires a continuous education and communication activity with the regulator. Because of the long time frames involved, the building structures continue to deteriorate slowly, and repairs and maintenance are required upon occasion. The costs can be significant, for example, to replace a roof. When these occasions arise, the balance of cost and benefit is always questioned, i.e., 'Wouldn't it be better to spend the money on dismantling rather than fixing?'. One positive note is that ancillary buildings that either have very low radiation hazards or were decontaminated during the initial decommissioning activities have been used for several alternate uses. This has helped to defray costs, and also keeps an interest in maintaining the building structures and systems in good condition during the SWS phase. Over the past few years, the lessons learnt from these and other facilities in SWS, have been addressed in a holistic manner by moving from a short-term, project-oriented approach to a comprehensive, long term stewardship approach. Key to this approach was the development of an integrated plan to decommission all of AECL's facilities. One of the prime results of the implementation of this plan was the development of an organizational structure that addressed the lessons learnt to date including information management, quality assurance, training, waste management, funding, etc. that are required to successfully maintain these prototype reactors until they can be fully decommissioned.
- Research Organization:
- American Nuclear Society, 555 North Kensington Avenue, La Grange Park, Illinois 60526 (United States)
- OSTI ID:
- 21144220
- Resource Relation:
- Conference: DD and R 2007: ANS Topical Meeting on Decommissioning, Decontamination, and Reutilization 2007, Chattanooga, TN (United States), 16-19 Sep 2007; Other Information: Country of input: France; Related Information: In: Proceedings of the 2007 ANS Topical Meeting on Decommissioning, Decontamination, and Reutilization - DD and R 2007, 336 pages.
- Country of Publication:
- United States
- Language:
- English
Similar Records
International Governmental Collaboration on Best Practice in Aging Infrastructure Management - 18027
Challenges for Lithuania: Ignalina NPP Early Closure